When data is transmitted as pulses of light along a fiber optic cable, chips at either end of that cable must convert the data from and back into an electronic signal - this is what allows an outgoing video image to be converted into light pulses, then back into video at the receiving end, for instance. There are a number of technical challenges in coupling chips to fibers, however. Now, an international team of scientists are developing an alternative ... fiber optics with the electronics built right into the fiber.
The main challenge regarding chips and optical fibers is a mechanical one - it's just plain difficult getting a round fiber to securely connect to a flat chip. It can also be quite a task making sure that all of the data gets from one to the other. An optical fiber is one-tenth the width of a human hair, while the light-guiding pathways on chips are even smaller, so getting everything lined up is a very fiddly business.
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For the research project, the team deposited semiconducting materials within tiny holes at either end of optical fibers, to create high-speed electronic junction points - these would ordinarily be located where the fiber meets the chip. The scientists used high-pressure chemistry techniques to deposit the materials directly, layer by layer. Not only does this eliminate the need for an entire chip in the finished product, but the process can also be carried out with simple inexpensive equipment, as opposed to the clean-room facilities required for chip manufacturing.
"If the signal never leaves the fiber, then it is a faster, cheaper, and more efficient technology," said team co-leader Pier J. A. Sazio, of the University of Southampton. "Moving technology off the chip and directly onto the fiber, which is the more-natural place for light, opens up the potential for embedded semiconductors to carry optoelectronic applications to the next level. At present, you still have electrical switching at both ends of the optical fiber. If we can actually generate signals inside a fiber, a whole range of optoelectronic applications becomes possible."
Some of these applications could include improved telecommunications, laser technology, and remote-sensing devices. It would be interesting to see if the new fiber could be incorporated into the hybrid cable being developed by Sandia National Laboratories, which is capable of transmitting both data and power.
The electronic fiber project was initiated and is being led by Pennsylvania State University, and was funded by the U.S. National Science Foundation and the Engineering and Physical Sciences Research Council of the United Kingdom.
Source: Penn State